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by remram 978 days ago
Can a user make a hard link to a file they don't own? How does this attack work?
2 comments
tadfisher 978 days ago
These links (pun unfortunate) should help:

https://sysctl-explorer.net/fs/protected_hardlinks/

http://michael.orlitzky.com/articles/posix_hardlink_heartach...

link
remram 977 days ago
Answer: fs.protected_hardlinks=1 is what prevents the creation of hardlinks to files you don't own. It's on by default on all machines I checked though.

https://github.com/torvalds/linux/commit/800179c9b8a1e796e44...

Without this, a whole lot of attacks are possible with hardlinks.

link